Various optical discs such as DVR have been proposed as disc-like recording media that can be loaded in and unloaded from a recording/reproducing device. The optical discs as such recording media have been proposed as media with a large capacity of several gigabytes or more and are expected to be media for recording audio/visual (AV) signals such as video signals.
As a coding system for digitally compressing AV signals, there is an MPEG (Moving Picture Experts Group) 2 system. This MPEG2 is a dynamic image compression format of an international standard aimed at realizing higher image quality by using compression techniques such as motion compensation prediction, DCT (discrete cosine transform), quantization and variable-length coding. The MPEG2 system is applied also in the case of recording AV signals to a recording medium. For example, when recording analog video signals to a recording medium, the video signals are encoded in accordance with the MPEG2 system and the coded bit stream is recorded to the medium. In the digital television broadcast, which has started recently, an AV stream coded in accordance with the MPEG2 system is transmitted in a format called “transport stream”. When recording the digital broadcast to a recording medium, it is considered that digital signals of a transport stream are directly recorded without being decoded and re-encoded.
In the case where AV signals are recorded to a recording medium in a digital signal format, it is possible to copy the AV signals to another recording medium without deteriorating the signals at all. However, this raises a serious problem for copyright holders of AV signals. Thus, in order to limit copying of AV signals, copy control information (CCI) indicating “Copy Free” (which means that copying is permitted), “Copy Once” (which means that copying of only one generation is permitted), “No More Copy (which means that copying of this and further generations is not permitted)”, or “Copy Prohibited” (which means that copying is prohibited) may be provided for AV signals.
For example, a system that is practically used for video signals at present is the CGMS (Copy Generation Management System). The CGMS is a system for controlling the number of times copying is permitted on the software side. The CGMS for analog interface is called “CGMS-A”, and the CGMS for digital interface is called “CGMS-D”. The analog CGMS-A is also called “VBID” because it superimposes an ID on a VBI (vertical blanking interval). This is standardized as EIAJ CP-1204. Moreover, in order to transmit copy control information in a transport stream, a method of coding a descriptor having copy control information is used. Descriptors of such types may be a DTCP descriptor prescribed by a DTLA (Digital Transmission Licensing Administrator) and a digital_copy_control_descriptor prescribed by the ARIB (Association of Radio Industries and Businesses) and used in the Japanese BS digital broadcast. Recently, in order to enforce further copy control, a system for embedding copy control information called “watermark” (WM) into base-band AV signals or MPEG AV streams is considered. Watermarking (WM) is now being standardized, and a millennium system and a galaxy system are proposed.
When recording AV signals to a recording medium, recording control must be accurately carried out in accordance with the copy control information of input signals. In general, in the case where a user recorded AV signals to a recording medium by using a recording device, the copy control information of the AV stream on the recording medium is either “Copy Free” (which means that copying is permitted) or “No More Copy” (which means that copying of this and further generations is not permitted). “No More Copy” results from updating of the copy control information when AV signals of “Copy Once” (which means only one generation of copying is permitted) are recorded.
Meanwhile, the increase in capacity of recording media enables recording of more AV streams to the recording media, as described above. In this case, the user needs to copy desired data of the AV streams from the respective discs. The user can copy AV streams having copy control information of “Copy Free”.
The increase in recording capacity of recording media enables continuous recording of AV streams for a longer time than before. In such a case, it is considered that a stream part of “No More Copy” and a stream part of “Copy Free” exist in one AV stream more often. For example, when two programs are continuously recorded, it may be considered that the first program is a material of “Copy Free” and the second program is a material of “Copy Once”.
Conventionally, in the case where a “No More Copy” stream part and a “Copy Free” stream part exist in one AV stream, the user cannot properly copy these parts to another recording medium. For example, if a “No More Copy” stream part exists at the beginning of one AV stream, the user cannot copy a “Copy Free” stream part at a halfway part in the AV stream. This is because it is difficult to know that plural pieces of control information exist in one AV stream, that is, to know that a “No More Copy” stream part and a “Copy Free” stream part exit in one AV stream. To know this, the user must read out the AV stream from the beginning to the end and analyze the copy control information. However, this analysis is time-consuming. Particularly with an AV stream of a long duration, it is difficult to read out all of the AV stream and grasp the presence of control information.